BREITHAUPT, brīt'houpt, Johann August Friedrich (1791-1873). A German mineralogist. He was born at Probstzella, Thuringia, and studied at the University of Jena, and at the Academy of Freiberg. Here he received an appointment in 1813 as teacher and lapidary, and in 1827 became professor. He wrote Ueber dieEchtheit der Krystalle (1816) and VollständigeCharakteristik des Mineralsystems (1820; 3d improved ed., 1832). He also continued Hoffmann's Handbuch der Mineralogie, adding five chapters to this valuable work. Toward the close of his life he became almost totally blind. He increased the nomenclature of crystallography, and introduced the so-called Progressionstheorie, which seeks to derive every species of crystal from a few isometric forms. He also carefully examined almost all the minerals known in his day, and took 3000 measurements of calcareous spar alone. The opening of the great coal-fields at Zwickau, in Saxony, was due to his initiative. His other publications include Die Paragenesisder Mineralien (1849) and Die BergstadtFreiberg (1825; 2d ed., 1847).